BREAKUP CONDITIONS OF PROJECTILE SPECTATORS FROM DYNAMICAL OBSERVABLES

Momenta and masses of heavy projectile fragments (Z greater than or eq ual to 8), produced in collisions of (197)AU With C, Al, Cu, and Pb ta rgets at EIA = 600 MeV, were determined with the ALADIN magnetic spect rometer at SIS. Using this information, an analysis of kinematic corre lations between the two and three heaviest projectile fragments in the ir rest frame was performed. The sensitivity of these correlations to the conditions at breakup was verified within the schematic sos model. For a quantitative investigation, the data were compared to calculati ons with statistical multifragmentation models and to classical three- body calculations. With classical trajectory calculations, where the c harges and masses of the fragments are taken from a Monte Carlo sampli ng of the experimental events, the dynamical observables can be reprod uced. The deduced breakup parameters, however, differ considerably fro m those assumed in the statistical multifragmentation models which des cribe the charge correlations. If, on the other hand, the analysis of kinematic and charge correlations is performed for events with two and three heavy fragments produced by statistical multifragmentation code s, good agreement with the data is found with the exception that the f luctuation widths of the intrinsic fragment energies are significantly underestimated. A new Version of the multifragmentation code MCFRAG w as therefore used to investigate the potential role of angular momentu m at the breakup stage. If a mean angular momentum of 0.75(h)over bar> /nucleon is added to the system, the energy fluctuations can be reprod uced, but at the same time the charge partitions are modified and devi ate from the data.